How threatened are we by Ebola virus?

The outbreak of Ebola in West Africa is a reminder that nature is our worst bioterrorist. Here, Nobel Prize winner Peter Doherty explains why we must be indefatigably watchful and prepared.

The Ebola outbreak affecting Guinea, Sierra Leone, Nigeria and now Liberia is the worst since this disease was first discovered over 30 years ago.

Between 1976 and 2013 there were less than 1,000 known infections; but according to the US Centers for Disease Control and Prevention (CDC), there have been 1,201 likely cases and 672 deaths between March and July 23, 2014.

The ongoing situation for these four West African countries is extremely dangerous, and there are fears that it could spread more widely in Africa. The relatively few intensive care units are being overwhelmed and the infection rate is likely being exacerbated by the fact that some who become ill are, on hearing that there is no specific treatment, electing to die at home surrounded by their family. The big danger is that very sick patients bleed, and body fluids and blood are extremely infectious.

Ebola cases are classically handled by isolation, providing basic fluid support, and "barrier nursing". Ideally, that means doctors and nurses wear disposable gowns, quality facemasks, eye protection and (double) latex gloves. That's why it is so dangerous for patients to be cared for at home.

But even when professionals are involved, the highest incidence of infection is normally in health care workers. A number of doctors have died in the current outbreak.

If there's any suspicion that travellers returning from Africa may be infected, it is a relatively straightforward matter in wealthy, well-organised countries like the USA and Australia to institute appropriate isolation, nursing and control. That's why the CDC believes that the threat to North America is minimal, with the same conclusion being equally applicable to Australia. As with so many other issues, the problem in Africa is exacerbated by poverty and the social disruption that goes with a lack of basic resources.

Given that this disease is not a constant problem for humans, where does it hide out? Fruit bats are thought to be the natural and asymptomatic reservoir but unlike the hideous, and completely unrelated, Hendra virus that causes somewhat similar symptoms, it is not in our flying foxes. And, while Hendra is highly lethal for horses, Ebola is killing off the great apes including our close, and endangered, primate relatives, the chimpanzees and gorillas.

The few human Hendra infections have been contracted from sick horses that were, in turn, infected from fruit bats. An "index" (first contact) human Ebola case could result from exposure to bat droppings, or from killing wild primates for "bush meat" - a practice that is, again, exacerbated by poverty. And, unlike Hendra, Ebola is known to spread from person to person.

The early Ebola symptoms of nausea, fever, headaches, vomiting, diarrhea and general malaise are not that different from those caused by a number of viruses, including severe influenza. But Ebola progresses to cause the breakdown of blood vessel walls and extensive bleeding. Also, unlike the fast developing influenza, the Ebola incubation period can be as long as two to three weeks, which means that there must be a relatively long quarantine period for suspected contacts.

Fortunately, and unlike influenza and the hideous (fictional) bat-origin pathogen depicted in the recent movie Contagion, Ebola is, in the absence of exposure to contaminated body fluids, not all that infectious. Unlike most such Hollywood accounts, Contagion is relatively realistic and describes how government public health laboratories like the CDC operate. It's worth seeing, and has been described as "the thinking person's horror movie".

Along with comparable agencies and the WHO, the CDC currently has about 20 people "on the ground" in West Africa. Other support is being provided by organizations like Doctors Without Borders, the International Red Cross and so forth. At this stage, there are no antiviral drugs available and no vaccine, though researchers in several institutions - including the US Vaccine Research Center in Bethesda, Maryland, and our own CSIRO Australian Animal Health laboratory (AAHL) - are working on the problem.

Largely as a consequence of their major success with Hendra and the closely related (from Malaysia) Nipah virus, AAHL has emerged as a major international centre for research on these bat-borne pathogens, with major triumphs being their development of monoclonal antibodies (mAbs) that can be used to treat patients and a Hendra vaccine for horses. However, it's much easier (and less expensive) to licence a vaccine for animals rather than people and, even if such a product becomes available for Ebola, the question of affordability for general use would be an issue for any African country.

Still, it would be a big plus if all African healthcare workers could be vaccinated. Monoclonal antibodies approved for emergency use could also be used to give those in contact "passive" protection for three or four weeks. These "miraculous mAbs" can now be developed and produced quickly, though they are very expensive.

What is being done? Neighbouring African countries are closing their borders; international agencies and governments are providing more professionals and other resources to help with treatment and tracking cases and contacts; global companies have been withdrawing their workers; and all nations are maintaining a close watch on air travellers who are arriving from, or have recently been in, these afflicted nations.

What is this Ebola catastrophe telling us? In these days of global cost cutting, we must keep our national and state public health services strong and maintain the funding for UN agencies like the OIE (World Organisation for Animal Health), the WHO and the FAO (Food and Agriculture Organisation). High security laboratories (BSL4) like AAHL are global resources, and their continued support along with the training and resourcing of the courageous and dedicated doctors (veterinary and medical) and researchers who work with these very dangerous pathogens is essential.

Humanity is constantly challenged by novel, zoonotic viruses like Ebola, Hendra, Nipah, SARS, MERS and so forth that emerge out of wildlife reservoirs, with the likelihood of such events being increased by extensive forest clearing, ever increasing population size and rapid air travel. We must be indefatigably watchful and prepared. Throughout history, nature is our worst bioterrorist.

Peter Doherty is a Laureate Professor at the University of Melbourne and the author of Pandemics: What Everyone Needs to Know (2013). He shared the 1996 Nobel Prize for Physiology or Medicine for his discoveries concerning immunity to viruses. View his full profile here.

Comments (50)

Comments for this story are closed.

Dave:

31 Jul 2014 3:44:17pm

Good article. Ebola is newsworthy because it is so spectacularly violent. It's unlikely to spread to the west or become a health issue here. But, as the author notes, it certainly highlights the power of nature to mess us right up.

While a novel influenza could certainly be a serious problem, for mine it's likely to be the rise of antibiotic-resistant bacteria which will do us more damage in coming decades. Got a cold? Your kid got the snuffles? Do you ask the doctor for antibiotics? Do you ever stop and ask why you're doing that and is it doing more harm than good? Perhaps you should.

Brian Francis:

31 Jul 2014 4:10:59pm

I feel so out of my depth commenting on this article, but it was, to me, enthralling reading.It makes me wonder, when I read of the diseases that can be transmitted, why in fact we don't see a lot more of the current type of out-break?Travel has never been so common and trade is possibly going further today also. Then there is the so called "Luxury" imports that become trendy(coffee/foodstuffs) and it does beg the question of why problems are not more common?

Dave:

31 Jul 2014 4:31:55pm

"It makes me wonder, when I read of the diseases that can be transmitted, why in fact we don't see a lot more of the current type of out-break?"

Viruses aren't even alive (exactly) but they are subject to evolution. Viruses like ebola are pretty new, very aggressive and, biologically speaking, not very successful. They rapidly kill their hosts and although they spread quickly they can be contained through good practice.

It's interesting that HIV has evolved to become less aggressive than when it first appeared (of course treatment has also improved). From a biological perspective, any given virus particle is now more likely to be able to spread and reproduce itself in new hosts, which is the biological objective of viruses.

DNA and the notion of the selfish gene is amazingly interesting and well worth reading up on.

Brian Francis:

01 Aug 2014 9:08:32am

Dave I guess that it's important that people such as yourself can keep this thing in perspective.My fear is that this may become another "SARS" and we will stop performing our daily functions in case we "Catch it".Governments and interested bodies are now going to struggle with this. When do we run?So many frightening things have been presented to us in recent times that, should there be a real threat to, let's say Australia; that we will simply not take any notice.Remember the Mr.Rudd episode of reminding us to wash our hands? That lost me.This may well be a forthcoming situation, but the information and the alerting of the public, needs to be handled very carefully.

Ann:

31 Jul 2014 7:45:50pm

Because this particular virus is kept in animal species that few humans have common contact with. How many people even in Africa eat fruit bats? And obviously millions of bats get eaten without causing a problem, so it's rare even there.

The fact is that most diseases that spread easily amongst humans, we have become relatively good at fighting off (or those that haven't, died).

The ones that hit us hard are the new/rare ones (remember it was only identified in the 70s, but that doesn't mean the virus didn't exist in some form before then), and there's always a reason why it's rare.

Judy Bee:

31 Jul 2014 4:16:28pm

Thank you for the article Peter. Those with a lust for cost cutting will only listen when something affects them personally or politically. Let us hope that Ebola which is now in Nigeria, and which incubates for 21 days, does not hop a plane to our shores. It could be here witin a day, and we wouldn't even know about it. Would our health services be prepared? I seriously doubt it.

whatif:

31 Jul 2014 5:41:11pm

This is frightening stuff and it makes one more aware of the danger as more and more people move about the world freely, what with flu's and other illness so prevalent today, it's only a matter of time before disaster strikes. lets hope we are up to the challenge .

Michael:

Sue:

31 Jul 2014 8:32:06pm

It always annoys me when I see environmentalists called haters of humankind. Preserving the environment is the best way to give mankind a liveable home for a very long time. Keep killing off the environment and humankind will also die.

Toc:

31 Jul 2014 8:37:48pm

Stating that the result of over-population is that a lot of people will die when we finally get to the end of our resource base, is not the same as wishing it would happen.Pretending it won't, guarantees it will.

Erik:

31 Jul 2014 10:25:22pm

Michael, the motivation which you ascribe to "environmentalists" reveals more about you than anyone else.

One reason why "environmentalists" might recognise merit in a bit of population thinning is that global population is growing at around 80 million per annum. Thus Australia's total food production, from here to eternity can only feed the last nine month's of population increase. Who will feed the next 90 month's swelling? No wonder we're eating gorillas, and catching Ebola.

Until we reduce population growth below zero, it is certain that _something_ _will_ raise the death rate, whether that be starvation, disease, or war. Failing to act _is_ a choice - that of increased deathrate.

Having no direct descendants, my personal investment in mankind's myopic madness is limited to intellectual curiosity. If "sovereign borders" gets a bit more serious in coming years, Australia ought to remain livable for my remaining years.

frangipani:

01 Aug 2014 12:12:05pm

Fertility rates are dropping in most parts of the world. It's a truism that as people become more prosperous, their birth rates drop. Add to that concerted efforts to educate women on contraception and you see the halving of birth rates even in impoverished countries like India.

The real problems nowadays are in sub Saharan Africa, and a few places like Afghanistan and Pakistan. Elsewhere, the numbers are going down quite quickly.

Dr Who:

01 Aug 2014 8:59:16am

Yes, it does sound misanthropic. But putting that aside, the answer to your question is: unlikely. Birth rates are highest in regions where life expectancy is low and childhood mortality is high. People want a successor; after pandemics abate, there is often a population surge (after all, when there's a 50% chance that any of your children will die from the bubonic plague, for example, you're more likely to have children survive you if you have twelve rather than just two).

It would take one mother of a pandemic to actually reduce the population to a sustainable level quickly. Far more effective would be to try to reduce the perceived (and in most cases, real) need for large families. Vaccination programs in developing countries are one of the cheapest means of doing so, and low-level developments (basic schools, clean water etc.) are also critical.

Not supporting governments or organisations that destabilize developing countries would also help; speak to Fairtrade advocates. I don't agree with their rabid anti-GM stance, but they will at least be able to point out who to steer clear of. The United Fruit Company (not overly relevant to us in Australia admittedly) is one such serial offender, which has been behind the ousting of several democratically-elected governments in order to install dictators in banana republics, and have actively held back development in these countries. Nestle also gets bad press for some of their activities (although I'm not aware of them actually ousting a government).

OUB :

31 Jul 2014 6:37:39pm

If we are looking for a positive ebola sounds like it is only infectious after the symptoms become obvious. It doesn't sound like those symptoms are easy to mistake for something else when the blood vessels break down and the bodily fluids escape.

The ABC story mentioned five types of ebola, some more dangerous than the others. Could the less harmful versions be used as a last resort immunisation measure in areas heavily affected by the more virulent versions?

Alpo:

Ann:

31 Jul 2014 7:49:15pm

Actually the first symptoms can just be things that feel like a flu. Even horrible vomiting and diarrhoea aren't enough to drive some people to seek out a doctor. It can be a day or two before the haemorrhaging starts.

Alpo:

31 Jul 2014 6:46:41pm

"Humanity is constantly challenged by novel, zoonotic viruses like Ebola, Hendra, Nipah, SARS, MERS and so forth that emerge out of wildlife reservoirs, with the likelihood of such events being increased by extensive forest clearing, ever increasing population size and rapid air travel."... This is an incredibly important point that I hope nobody misses just because it's at the end of the article.Thanks for this contribution, Peter. As academia is currently under attack, it's so important that high quality academics show why research is such an essential requirement for a country to be successful.

Sue:

Lachie:

31 Jul 2014 8:02:00pm

As you would expect from its internationally respected author, this is one of the best articles on this site I have seen.Having said that and as a former Quarintine advisor to the Fed Ag Mnister I must to draw attention to the impact of other imported diseases, perhaps less dramatic, which we face.

Diseases such as influenza cause more loss of productivity. Foot and mouth potentially a greater economic impact. And preventable heart disease a greater loss of life.

So while the basic premise of this article is spot on, keep our national and surveillance systems strong, we must not be distracted from the basic endemic problems which we face.

But well done to the author. If scientists like him do not speak up we are surely lost!

Judy:

31 Jul 2014 8:09:48pm

Yes, it is a good article but Dave in his comment says "..it certainly highlights the power of nature to mess us right up." I totally disagree. We humans have totally messed nature up so that all the natural checks and balances are out of kilter.

Peter Doherty points this out by writing "zoonotic virus like Ebola, Hendra ... and so forth ... emerge out of wildlife reservoirs, with the likelihood of such events being increased by extensive forest clearing, ever increasing population size and rapid air travel."

It is unfortunate that he says throughout history nature has been "our worst bioterrorist". In a way that is true but it is largely through our often destructive and ignorant interaction with nature.

Dave:

01 Aug 2014 10:10:40am

"We humans have totally messed nature up so that all the natural checks and balances are out of kilter."

In some ways I share this view, but the ebola breakout is not an example. There have always been novel virus strains which are very bad for their hosts, be the host an animal or plant, and the usual (not always) story is that these viruses evolve to become less harmful/better coexistant. This phenomenon predates humans altogether, let alone civilisation let alone our more recent high-impact activities.

P.Woods.:

31 Jul 2014 8:22:16pm

Having recently been in Sierra Leone 3 times the last visit in early July and prior to that in April & June ,2014 I am amazed at the lack of action by President Karoma. Quarantine should have been implemented immediately and a lock down Policy put in place plus intra Country Travel restricted.Air travel and Border Closure is the only way to containment and I am surprised that International Flights have not been curtailed long ago. The WHO are seemingly reticent to ban travel to and from the Countries that are experiencing this current outbreak - why is that? This virus has the potential to decimate populations not just in West Africa with its limited facilities.Some Companies in the Mining Sector have sent staff back to the UK etc.long ago.All Air travellers should have a mandatory Medical appraisal and not allowed to depart for a foreign destinations unless certified free of the virus and that stamped in their travel documents.

P.Woods.:

31 Jul 2014 8:27:57pm

Having recently been in Sierra Leone 3 times the last visit in early July and prior to that in April & June ,2014 I am amazed at the lack of action by President Karoma. Quarantine should have been implemented immediately and a lock down Policy put in place plus intra Country Travel restricted.Air travel and Border Closure is the only way to containment and I am surprised that International Flights have not been curtailed long ago. The WHO are seemingly reticent to ban travel to and from the Countries that are experiencing this current outbreak - why is that? This virus has the potential to decimate populations not just in West Africa with its limited facilities.Some Companies in the Mining Sector have sent staff back to the UK etc.long ago.All Air travellers should have a mandatory Medical appraisal and not allowed to depart for a foreign destinations unless certified free of the virus and that stamped in their travel documents.

Kevin52:

31 Jul 2014 9:44:36pm

What I find frightening is the fact that Australian authorities were completely ineffective at keeping swine flu out of this country.I therefore have not faith in them keeping out something more terrible, such as a variant of ebola.

observer:

31 Jul 2014 10:42:47pm

Good article - the AIDS came out of Africa and what is clear that the world is very connected, so what happens in one part of the World affect us all in some way. The other important point is that the free market is not going to fix what is a social problem - there's not enough money in it. Hence, each country needs a strong government funded health service and associated government funded research units. The worrying thing is that western governments are about cutting budgets cutting taxes, reducing the size of government in name of efficiencies. All of these viruses start in the poorer sections of society, because there is little or no money for health care, and poor education. And it's not just viruses which cause a problem it's also antibiotic resistant strains of bacteria. A nations productivity is totally dependent on the heath and education of its citizens.

Abel Adamski:

01 Aug 2014 1:42:17am

Worth considering what could happen.Of the first world developed Nations the US is at the greatest risk due to their health system and a large section of the population below the poverty level. Too many cannot afford a doctors visit or an Emergency visit or any tests or medication. It would spread like wildfire amongst the US's low income workers and disadvantaged, many work in the food industry , as cleaners, porters, hotel maids etc. They travel to work on public transport. The first authorities would know is when the bodies start piling up nationwide, they could make all sorts of demands of the citizens, but if you can't pay for the health services the demands are wasted hot air.Unfortunately our government and private healthcare companies and organisations with their greed and ideology are taking us down the path of National vulnerability also

Peter:

01 Aug 2014 1:59:52am

Yep a big problem. All the nutters in the middle east and north africa should be left alone to do what they do best.Kill each other in the name of alla. The West should let these nutters kill each other and let the winning tribes take benefits as victors. No more aid should be sent from the West as it will make no difference. I lived in Cairo and had a guy call on me selling a bag of flour clearly marked as a "gift of the US"

ianh:

01 Aug 2014 7:12:27am

As some one involved in the swine flue outbreak in Australia, let me add that no Australian health authority or government has the balls or the resources to respond in anything approaching what is needed in any serious health emergency. Ebola or anything else. While they have the skills and expertise it is the will that is lacking. We have all been lucky that until now that death rates have been so low, Spanish flue had a death rate of 3 % or so and that killed millions around the world, there was no air travel then. If you really want to scare yourselves look at the Plague Inc, a computer game available on Steam. All air traffic and shipping out of all effected countries needs to be stopped immediately

Peter of Melbourne:

01 Aug 2014 11:17:02am

most of this nations issues could be solved if we had a conbination of political willpower and political competence... sadly as has been shown for the past two decades finding a combination of the two is extremely rare in australian politics and you have a better chance of winning division 1 in the lotto

VetTeacher:

01 Aug 2014 7:36:43am

From what has been written, the difference between this epidemic of Ebola and previous outbreaks is the higher incidence of the disease in metropolitan areas. High mortality rates are apparently in line with expections but the much larger number of victims has the potential to overwhelm available resources.

Even the poorest nations of equitorial Africa have transport systems capable of moving people around the affected region rapidly. A long incubation period between being infected and displaying symtons has the obvious potential for the virus to move considerable distances before being detected.

If this thing ever aquired the ability to spread without the need for direct contact everybody would be in trouble. Developed nations have largely wiped out infectious diseases by spending a lot of money on high quality public health. Unfortunately this approach is under challenge from governments questioning the need to take these precautions.

Bubonic plague is a disease most Australians would believe has been completely defeated. Not true and it is only the existence of antibiotics which keeps this scourge in check when outbreaks occur. That along with stringent public health initiatives.

The developed world needs to spend the money and supply the resources to the countries affected by VHF diseases before the genie is out of the bottle. Slashing money for overseas aid may not be the smartest decision after all.

I wonder how many doctors in Australia, either in casualty departments or general practice have ever seen Ebola or would be looking for it when a person prevents with severe flu symptoms.

Peter of Melbourne:

01 Aug 2014 11:22:51am

@vetteachernope the developed world does not need waste any more resources or funds on the 3rd world and in fact needs to completely isolate the 3rd world until1. they either settle all of their tribal/religious conflicts internally, or 2. else agree to settle them by stringent 1st world conditions.

there is not a reason in the world to continue wasting resources on failed societies who have no interest in helping themselves.

vic:

01 Aug 2014 9:44:23am

Re the Ebola story, My understanding is that "bushmeat" is becoming a luxury item in some wealthy parts of Africa and I have read reports of illegal shipments being intercepted entering the UK, so I would not be too complacent that it can't happen here, or at least in the west somewhere. I do agree that our medical system should be able to handle it although a couple of recent involvements with major hospitals suggests this may be just the triumph of hope over experience.

Bruce:

The nose:

01 Aug 2014 10:25:50am

These infectious viruses appear to attack countries that are poor and where Goverments are corrupt. Papua New Guinea is an example where even though the Goverment were warned about the threat of aids they ignored it and harassed people who dared raise the issue.In this country we have a Goverment who is hell bent on deregulating everything and cutting back on research, so that business can take over and Goverment can get out of the way.Yes, welcome, Ebola! We are about to create an environment which wil be conducive for you to do your handy work.

frangipani:

Pedro Pesce:

01 Aug 2014 11:23:07am

The good professor's article - informative as it is - is all about cure - not prevention. Anyone with even a slight exposure to medicine and health will already know a more holistic approach is more successful. What seems missing in this discussion is dealing with the sources and conveyancy of the virus. Source: fruit bats. Conveyancy - eating 'bush meat' of the secondary hosts apes. Do we allow the logic as applied to WA's shark cull to these fruit bats? This is their natural environment, we humans have 'dared' to enter it, thus we must take nature's consequences come what may; just so the fruit bat population is not threatened, we must potentially die by the millions and actually die by the hundreds? So just don't go there in this politically correct world; let's just make the whole focus on treatment then! Taking it to an extreme admittedly, but it just gives a glimmer illustrating how the green movement's illogical view of the world of nature is so flawed and how they dangerously mute a very necessary debate. I even see the odd post here with the crackpot nuance 'we must die in order to save the planet'. (Must be a pity for the likes of you that Nitschke has just been put off line). We will go in our own good time no doubt, extinction being the norm in nature; but not without a fight - and pointing out the erroneous nature of this conservation and misanthropic lunacy is a start. The stakes here are too extraordinarily high for any high-minded, holier than thou moralizing - Russian roulette with 5 out of six chambers filled.

The UN should do its true job protecting the global population by ensuring these particular populations of fruit bats are immediately exterminated to eradicate the viral source as much as possible. Using the philosophy that an ounce of prevention is worth a pound of cure, and current first world health policy strategies of preventative health measures, a massive education roll-out - think anti-smoking campaign - to local populations in the affected areas as to the danger of procuring and eating bush meat should be the first priority. Professor Doherty says there are professionals already on the ground there, so why not? Bring in fines and imprisonment. We do already for illegal drug use. We can't pussy-foot around with this situation. We must ensure that this is not another case repeating the routine human behavioural pattern of putting the traffic lights in after the accident: the WHO's reaction of not restricting access to and from the area looks awfully lackadaisical. Except dallying on this one could allow a mass extermination event making the 1919 influenza pandemic and the medieval and 1616 plagues look like a walk in the park. We should be extremely concerned and worried. And we need a multifaceted 'desperate times call for desperate measures' rather than a purely treatment based approach to ensure any chance of success.

Dave:

01 Aug 2014 3:03:28pm

"ensuring these particular populations of fruit bats are immediately exterminated to eradicate the viral source as much as possible"

Do we know for certain that these fruit bats aren't performing vital tasks in the ecosystem? They might be critical for some plants to reproduce by spreading their seeds in s certain fashion, they might be controlling otherwise difficult insect populations, they might be squeezing a nasty competitor out of an otherwise welcoming environment.

If I eradicate the world's bee population to address the problems of bee stings and related allergies, then the world's crops won't pollinate. Is that smart or dumb? Cane toads were introduced to Australia based on similar logic to your post. Smart or dumb?

VetTeacher:

01 Aug 2014 4:11:51pm

The whole thrust of my post was to highlight the danger to the world posed by a disease difficult to detect in its early contagious stages and which with jet travel could find its way around the globe in no time.

I am not pushing for more aid for third world countries only for a sensible response to a rapidly deteriorating situation which poses a real threat to regions far removed from the current centre of the outbreak.

Assisting the inadequate public health services of these countries is not charity it is a sensibly self-interested response to a known threat. All of the old infectious diseases which posed a real theat even in my childhood have been brought under control by sensible public health policies. This one is not just a case of a course of streptomycin ( as in Bubonic plague) because antibiotics do not work on viruses.

When the disease appears on your doorstep, it is not the best time to find out if your first world level of public health is actually up to taking the disease head on and coming out on top.

Someone:

01 Aug 2014 4:35:39pm

I'd like to know if there are more reasons for why this has gotten so out of control outside of people wanting to die at home. I have heard that health workers are being attacked by locals believing that they are the cause. They're often mistrusted and there's a lot of superstition surrounding the handling of the virus.

It seems like spreading information might be the best way to stop this from getting worse.